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[VtArray] Add zero-copy withUnsafeBufferPointer and single-copy buffer init #39

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[VtArray] Add zero-copy withUnsafeBufferPointer and single-copy buffer init #39

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4 changes: 4 additions & 0 deletions SwiftUsd.docc/AboutThisRepo/ChangeLog.md
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Expand Up @@ -11,6 +11,10 @@ Changes to SwiftUsd
```
}

### TBD
Released TBD, based on OpenUSD TBD
- Add zero-copy `VtArray` reads via `withUnsafeBufferPointer(_:)` and single-copy construction from an `UnsafeBufferPointer`

### 8.0.0
Released 2026-07-22, based on OpenUSD v26.08
- Add support for writing, distributing, and using OpenUSD plugins in Swift/C++ with Swift Package Manager
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47 changes: 47 additions & 0 deletions source/SwiftOverlay/VtArray.h
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@@ -0,0 +1,47 @@
//===----------------------------------------------------------------------===//
// This source file is part of github.com/apple/SwiftUsd
//
// Copyright © 2025 Apple Inc. and the SwiftUsd project authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// SPDX-License-Identifier: Apache-2.0
//===----------------------------------------------------------------------===//

#ifndef SWIFTUSD_SWIFTOVERLAY_VTARRAY_H
#define SWIFTUSD_SWIFTOVERLAY_VTARRAY_H

#include <type_traits>
#include "pxr/base/vt/array.h"

namespace __Overlay {
// expose `assign` in a way Swift will import. VtArray uses copy-on-write
// storage, so this constructs the array with a single copy of the source
// range, rather than the element-by-element push_back the Collection
// initializer falls back to.
//
// Swift 6.3 fixes https://github.com/swiftlang/swift/pull/82161, but on Swift 6.1 and Swift 6.2,
// templated methods taking pointers without nullability annotations are assumed to be non-null,
// and templated methods taking pointers with nullability annotations aren't imported. So,
// use ptrdiff_t instead
template <typename VtArray>
inline void VtArray_assign(VtArray& array, ptrdiff_t frontPtr, ptrdiff_t backPtr) {
using Element = typename VtArray::ElementType;
static_assert(std::is_same_v<VtArray, pxr::VtArray<Element>>);
const Element* front = reinterpret_cast<const Element*>(frontPtr);
const Element* back = reinterpret_cast<const Element*>(backPtr);
array.assign(front, back);
}
}

#endif // SWIFTUSD_SWIFTOVERLAY_VTARRAY_H
292 changes: 246 additions & 46 deletions source/SwiftOverlay/VtArrayProtocol.swift
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Expand Up @@ -106,12 +106,21 @@ extension __Overlay {
associatedtype ElementType
func __beginUnsafe() -> UnsafePointer<ElementType>?
func __endUnsafe() -> UnsafePointer<ElementType>?

func __cdataUnsafe() -> UnsafePointer<ElementType>?
func size() -> Int

mutating func __assign(_ p: UnsafeBufferPointer<ElementType>)
}
}
extension __Overlay.VtArray_Sequence where Element == Self.ElementType {
public func makeIterator() -> __Overlay.VtArray_Sequence_Iterator<Self> {
.init(begin: __beginUnsafe(), end: __endUnsafe(), s: self)
}

public borrowing func withUnsafeBufferPointer<T, E>(_ code: (UnsafeBufferPointer<ElementType>) throws(E) -> T) throws(E) -> T {
try code(UnsafeBufferPointer(start: __cdataUnsafe(), count: size()))
}
}

extension __Overlay {
Expand All @@ -132,65 +141,256 @@ extension __Overlay {
}
}

extension pxr.VtBoolArray: __Overlay.VtArrayProtocol {}
extension pxr.VtDoubleArray: __Overlay.VtArrayProtocol {}
extension pxr.VtFloatArray: __Overlay.VtArrayProtocol {}
extension pxr.VtHalfArray: __Overlay.VtArrayProtocol {}
extension __Overlay.VtArrayProtocol {
public init(_ buffer: UnsafeBufferPointer<ElementType>) {
self.init()
self.__assign(buffer)
}
}

extension pxr.VtCharArray: __Overlay.VtArrayProtocol {}
extension pxr.VtUCharArray: __Overlay.VtArrayProtocol {}
extension pxr.VtShortArray: __Overlay.VtArrayProtocol {}
extension pxr.VtUShortArray: __Overlay.VtArrayProtocol {}
extension pxr.VtIntArray: __Overlay.VtArrayProtocol {}
extension pxr.VtUIntArray: __Overlay.VtArrayProtocol {}
extension pxr.VtInt64Array: __Overlay.VtArrayProtocol {}
extension pxr.VtUInt64Array: __Overlay.VtArrayProtocol {}
extension pxr.VtBoolArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtDoubleArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtFloatArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtHalfArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtVec4iArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec3iArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec2iArray: __Overlay.VtArrayProtocol {}
extension pxr.VtCharArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtUCharArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtShortArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtUShortArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtIntArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtUIntArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtInt64Array: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtUInt64Array: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtVec4hArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec3hArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec2hArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec4iArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec3iArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec2iArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtVec4fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec3fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec2fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec4hArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec3hArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec2hArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtVec4dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec3dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec2dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec4fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec3fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec2fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtMatrix4fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix3fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix2fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtVec4dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec3dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtVec2dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtMatrix4dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix3dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix2dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix4fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtMatrix3fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtMatrix2fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtRange3fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRange3dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRange2fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRange2dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRange1fArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRange1dArray: __Overlay.VtArrayProtocol {}
extension pxr.VtMatrix4dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtMatrix3dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtMatrix2dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtRange3fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRange3dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRange2fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRange2dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRange1fArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRange1dArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtIntervalArray: __Overlay.VtArrayProtocol {}
extension pxr.VtRect2iArray: __Overlay.VtArrayProtocol {}
extension pxr.VtIntervalArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtRect2iArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

// VtStringArray gains Codable conformance in Codable.swift,
// but it can't satisfy the requirements that ElementType is Codable
// because std.string isn't Codable
extension pxr.VtStringArray: __Overlay.VtArray_WithoutCodableProtocol {}
extension pxr.VtTokenArray: __Overlay.VtArrayProtocol {}
extension pxr.VtStringArray: __Overlay.VtArray_WithoutCodableProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtTokenArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtQuathArray: __Overlay.VtArrayProtocol {}
extension pxr.VtQuatfArray: __Overlay.VtArrayProtocol {}
extension pxr.VtQuatdArray: __Overlay.VtArrayProtocol {}
extension pxr.VtQuaternionArray: __Overlay.VtArrayProtocol {}
extension pxr.VtQuathArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtQuatfArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtQuatdArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}
extension pxr.VtQuaternionArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension Overlay.SdfAssetPath_VtArray: __Overlay.VtArrayProtocol {}
extension Overlay.SdfAssetPath_VtArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}

extension pxr.VtTimeCodeArray: __Overlay.VtArrayProtocol {}
extension pxr.VtTimeCodeArray: __Overlay.VtArrayProtocol {
public mutating func __assign(_ p: UnsafeBufferPointer<ElementType>) {
__Overlay.VtArray_assign(&self, Int(bitPattern: p.baseAddress), Int(bitPattern: p.baseAddress.map { $0 + p.count }))
}
}